Editor's note: This post was edited to correct the full name of the complex where the fire occurred.

Stonington — Firefighters spent several hours on Wednesday battling a blaze in a portion of the former Thread Mill complex in Pawcatuck.

Witnesses familiar with the layout of the mill said the fire appeared to be contained to the area of a printing business, Emulsion Printhouse, which is located on the upper floor in the southern half of the sprawling complex off Pawcatuck Avenue and River Road.

The northern portion of the mill, currently being converted into apartments, was not affected by the fire. No injuries were reported.

The extent of the damage was unclear Wednesday evening and a representative from the Pawcatuck Fire Department was not immediately available for comment.

One witness said he had just walked into Fabrigraphics, an embroidery business located inside the mill, at 4:05 p.m. when the fire alarms sounded inside the building.

The building immediately was evacuated; smoke, and later flames, could be seen coming from the windows of the upper floor.

Firefighters still were fighting hot spots with dusk approaching, accessing the upper floors and roof from several different ladder trucks.

Pawcatuck firefighters were joined by the Mystic, Old Mystic, Westerly, North Stonington and Dunn’s Corner fire departments, among others.

g.smith@theday.com

Twitter: @SmittyDay

A firefighter ventilates the roofline as crews battle a fire in the upper floors of the former mill building at 21 River Rd. in Pawcatuck, Wednesday, May 27, 2015. (Sean D. Elliot/The Day)

Firefighters ascend a tower ladder to battle a fire in the upper floors of the former mill building at 21 River Rd. in Pawcatuck, Wednesday, May 27, 2015. (Sean D. Elliot/The Day)